RU2198185C2 - Reactive heterochain oligomers based on proton-containing acrylic derivatives and method of their synthesis - Google Patents

Abstract

FIELD: organic chemistry, polymers, chemical technology. SUBSTANCE: invention describes reactive heterochain oligomers based on proton-containing acrylic derivatives of the general formula: CH₂= CH-C(O)O-(CH₂)_n-X-

Description

 The invention relates to new heterochain reactive oligomers and a method and their preparation. The synthesized macromonometers can be used to obtain new polymers, as well as modifying additives, surfactants, resins, compatibilizers in the preparation of polymer mixtures, coatings in electrical engineering, electronics, materials science.

It is known that (meth) acrylates are polymerized by radical and ionic mechanisms with the opening of a double bond and the formation of high molecular weight carbochain polymers [Encyclopedia of Polymers. M .: ed. "Soviet Encyclopedia". T. 1.P. 31-33. 1972.]
There is evidence of the polymerization of hydroxyethyl (meth) acrylate or their analogs by the radical mechanism [US Pat. No. 4,157,892, 06/12/1979.] By radiation initiation [US Pat. No. 4,904,708, 02/27/1990.] Or by the action of photoinitiators [US Pat. No. 5681871, 10/28/1997 ] with the formation of high molecular weight carbochain polymers used as the basis of contact lenses, as well as the use of hydroxyl-containing (meth) acrylates as additives to epoxy (meth) acrylate resins to reduce viscosity [German Patent 3334329, 09/22/1982.] or as component in composition uu with diamines [US Patent 5830987, 26.01.1995.].

 Of the derivatives of (meth) acrylates, only acrylamide is capable of polymerizing under the action of ion initiators with the formation of the corresponding hetero-chain high molecular weight polymers [Encyclopedia of Polymers. M .: ed. "Soviet Encyclopedia" T. 1. P. 30-31. 1972.].

 Thus, no information was found on the preparation of low molecular weight reactive hetero chain oligomers based on proton-containing (meth) acrylic derivatives.

Closest to the claimed technical solution are macromonomers based on derivatives of (meth) acrylates and the method for their preparation [US Patent 5147952, 09/15/1992.]. In this case, anionic polymerization is carried out using a pre-synthesized structure initiator:
CH ₂ = CH — C (O) O— (CH ₂ ) _n —C ^- (R ₁ ) (R ₂ ) M +,
where R ₁ and R ₂ are electrophilic groups stabilizing the carbanion C ^- , M + is a quaternary ammonium ion. The process is carried out in an organic solvent at 0-60 ^o C. As a result, macromonomers of the carbochain structure (heterochain only at the end of the chain) with one terminal reactive group and a molecular weight of from 2000 to 10000 (depending on the amount of initiator) are obtained.

 The disadvantages of this method are the preparation of carbochain macromonomers with only one terminal reactive group and the need for preliminary synthesis of an expensive initiator of a complex structure.

 The presence of reactive groups of various nature at the ends of the chain presents a wide range of possibilities for macromolecular design and, in this way, to obtain polymer matrices and modifiers of various structures, in addition, the heterochain structure of the polymer molecule provides specific properties compared to the carbolic chain.

 The objective of the invention is the creation of new reactive heterogeneous oligomers - macromonometers with two terminal reactive groups and a weight average molecular weight of not more than 3000.

The problem is solved by oligomerization of proton-containing acrylic derivatives to obtain heterocentric reactive macromonomers of the general formula:
CH ₂ = CH-C (O) O- (CH ₂ ) n-X- [CH ₂ -CH ₂ -C (O) O- (CH ₂ ) _n -X-] _m H,
where X- —O—, —O — C (O) —N (Ph) -; n is 2-10; m = 2-15.

 These chemical compounds with a polyester or urethane backbone have two reactive groups at the ends of the chain (double acrylic bond and functional). Note that the presence of a functional group in the proposed macromonomers significantly expands the structural modification of both the macromonomers themselves and the polymers based on them. In essence, it is possible to create a new class of macromonomers based on acrylic derivatives with an active proton in the structure of the molecule.

 The essence of the proposed technical solution lies in the fact that upon receipt of reactive hetero chain oligomers by anionic polymerization of acrylic derivatives in the presence of an initiator, proton-containing acrylic derivatives are used as monomers, anionic polymerization is carried out in an inert medium in the presence of initiators selected from the group: alkali metals or their derivatives, a mixture of α-oxide and a tertiary amine, the molar ratio of components in which they are taken in the range of 0.5-1.5; moreover, the ratio of monomer and initiator is selected from the interval (10-40) ÷ 1, respectively.

For example, to obtain oligomers of the above structure, monomers of the following formula can be used:
CH ₂ = CH C (O) O (CH ₂ ) _n OH
CH ₂ = CHC (O) O (CH ₂ ) _n OC (O) NHPh,
where n = 2-10.

The synthesis is carried out in an inert medium with constant stirring in the temperature range of 40-80 ^o C to obtain the target product.

With an increase in the initiator content in the reaction mixture with respect to the monomer (> 10 mol% of the monomer concentration), chain growth is not realized, with an initiator content of less than 2.5 mol%, the number of active centers required to obtain the oligomer is not provided. At a temperature of <40 ^° C, the initiation of oligomerization is significantly slowed down, and at a temperature of> 80 ^° C the contribution of side reactions that degrade the molecular characteristics of the oligomer and its distribution by type of functionality increases. If α-oxide and a tertiary amine are used to initiate a mixture, the ratio of 1 ÷ 1 is preferable, since the formation of an active center, tetraal-ammonium alcoholate, requires an equifunctional ratio of these reagents [Kushch P. P., Komarov B. A., Rosenberg B. .A. The role of proton donor compounds in initiating the polymerization of epoxy compounds with tertiary amines. // High Molecule. conn. A. 1979. T. 24. 2. S. 1697].

Using the described process of anionic polymerization, soluble oligomers are formed with a number average molecular weight (M _N ) in the range of 500-1500 and a molecular weight distribution (MMP) close to the most probable (M _W / M _N = 2). To confirm the structure and determine the molecular characteristics of the oligomers, NMR spectroscopy and gel permeation chromatography (GPC) were used on a Waters instrument with refractometric (DR 410) and ultraviolet (PDA 996) detectors, which made it possible to obtain UV spectra of each oligomer fraction in the region 210-290 nm (for tetrahydrofuran (THF)) and identify the presence of a double bond at the peak with a wavelength of 210-213 nm. The average values of Mn and Mw are calculated using a calibration curve according to polystyrene standards.

 The essence of the invention is demonstrated by the following examples.

Example 1. Samples of hydroxyethyl acrylate (HEA) - 4.94 g and a solution of lithium tert-butylate in toluene (titer 3 • 10 ^-4 mol / ml) - 6.86 g are placed in a glass ampoule in a stream of argon at room temperature. After additional air displacement with argon, the ampoule is sealed, thermostated at 80 ^o C for 70 hours. After cooling, the ampoule is opened, the reaction mixture is neutralized by adding 0.3 ml of glacial acetic acid and 20 ml of a 10% solution of potassium hydrogen sulfate. After shaking, the mixture is poured into a separatory funnel, where it is held for three days until it is clearly divided into three layers: the lower layer is the GEA oligomer, the middle layer is a solution of lithium acetate and sulfate in water; the top layer is a solution of unreacted GEA in toluene. After separation, the oligomeric layer is subjected to vacuum drying at a temperature of not more than 50 ^o C for three hours to a residual pressure of 0.1 mm RT. Art. The result of GPC analysis of the obtained oligomer is presented in the table.

Example 2. Samples of GEA - 5.00 g, phenyl glycidyl ether (PGE) - 0.729 g and dimethylbenzylamine (DMBA) - 0.505 g are poured into a glass ampoule in a stream of argon at room temperature. The process is conducted in an inert atmosphere for 24 hours at 50 ^o C. After the end of the process, the reaction product is analyzed by GPC, the results are presented in the table.

Example 3. Samples: GEA - 1.856 g, PGE - 0.246 g and DMBA - 0.213 g are used to synthesize the oligomer as in Example 2. Thermostating for 96 hours at a temperature of 80 ^o C. After the reaction, DMBA and soluble fractions are washed out with two 10 10 -fold portions of ethyl alcohol for three days at room temperature. The oligomer and its fraction washed with ethyl alcohol are dried in vacuum at room temperature and analyzed by GPC (results in the table) and NMR spectroscopy.

 Example 4. Use samples of phenylurethane ethylene acrylate (FUEA) - 0.846 g, PGE - 0.059 g and DMBA - 0.049 g to obtain the FUEA oligomer as in Example 3. Low molecular weight products are washed with four portions of a hundred-fold excess of ethyl alcohol at room temperature for ten days. The washed oligomer is analyzed by GPC (results in the table) and NMR spectroscopy.

Example 5. The FUEA oligomer is obtained as in Example 4 except for thermostating condition: for 70 hours at 70 ^o C. The oligomer is analyzed by the thermomechanical method (UIP-70 device) and GPC method.

 Example 6. The FUEA oligomer is synthesized according to the conditions of Example 5. The oligomer, washed from low molecular weight fractions, is analyzed by NMR and GPC using two portions of a ten-fold excess of ethyl alcohol for three days.

Example 7. The FUEA oligomer is synthesized according to the conditions of Example 5. After drying in vacuum, the oligomer is further aged for seven hours at 100 ^o C. The result of GPC analysis is presented in the table.

Example 8. The FUEA oligomer is synthesized analogously to example 4 except for the ratio of reagents [С = С] о / [ФГЭ] о = 17.1, [ФГЭ] о = [DMBA] о and the reaction mode: at 80 ^o С for 24 hours . GPC analysis is presented in the table.

 Example 9. The FUEA oligomer is synthesized analogously to example 8 except for the molar ratio of reagents [C = C] o / [PGE] o = 36.5, [PFE] o / [DMBA] o = 0.5. GPC data in the table.

Example 10. As a monomer, 3-hydroxypropyl acrylate (GPA) was taken, 1.95 g of the initiator was lithium tert-butylate 0.06 g. The oligomer was synthesized without solvent at 50 ^° C for 48 hours with constant stirring under a stream of argon. The reaction mass is dissolved in methylene chloride and neutralized with carbon dioxide to a pH of ~ 7.0, then filtered and the solvent removed in vacuo. Yield 83%. Molecular characteristics are given in the table.

Example 11. Take samples: GEA - 4.66 g, tetrahydrofuran (THF) - 18.66 g and potassium metal - 0.157 g. The synthesis of the oligomer is carried out in a flask under reflux with constant stirring in an argon stream at a boiling point THF (≤66 ^o C) for 6 hours. After neutralizing the reaction medium with carbon dioxide to a pH of ~ 7.0 and filtering, an oligomer is isolated. Yield 72%. Molecular characteristics are given in the table.

 The table shows that the proposed method forms oligomers with a weight average molecular weight of ≤ ~ 3000 and an MMP close to the most probable. An exception is the data of examples 2,8 and 9, in which oligomers with MMP> 2 are formed due to the incompleteness of the process (lower temperatures, initiator concentrations and shorter thermostating times).

When oligomerization of hydroxyl-containing acrylates with alkali metals is initiated, alkoxides are formed in the reaction medium, the alkoxy anions of which can attack the double bond of the monomer on the α-carbon atom and cause chain growth, which leads to the presence of one terminal C = C bond in the macromolecule with the hetero-chain structure of the oligomer. Upon initiation of lithium tert-butylate due to a significant difference in the acidic properties of primary and tertiary alcohols (respectively, the basicity of their alkoxy anions increases with decreasing alcohol acidity R ₃ СОН> R ₂ OH> RCH ₂ O), the equilibrium is rapidly shifted towards the formation of hydroxyl-containing acrylate alkoxyan anions . Due to its low basicity, tertbutoxyanion is not able to attack the C = C bond of the monomer and initiate the oligomerization process. The absence of a terminal tert-butoxy group in the resulting oligomers was established experimentally.

 It is known that tertiary amines are not able to cause the polymerization of epoxy compounds such as glycidyl ethers in the absence of a proton donor compound (PS), and if it is present, chain growth begins with the alkoxyanion of tetraalkylammonium alcoholate formed from the used PS, α-oxide and tertiary amine [Kushch P. P ., Komarov B.A., Rosenberg B.A. The role of proton donor compounds in initiating the polymerization of epoxy compounds with tertiary amines. // High Molecule. conn. A. 1979. T. 24. 2. S. 1697; Komarov B.A. , Kushch P.P., Rosenberg B.A. Kinetic laws of polymerization of phenyl glycidyl ether under the action of tertiary amines. High mole. conn. A. 1984. T. 26. 8. S. 1732; Komarov B.A., Kush, P.P., Rosenberg B.A. Reactivity of free ions and ion pairs of active polymerization sites of phenyl glycidyl ether under the action of tertiary amines in proton media. High mole. conn. A. 1984. T. 26. 8. S. 1747]. In our case, the monomer itself plays the role of PS, which ultimately leads to a similar chain nucleation mechanism with a terminal acrylate C = C bond in the macromonomer with> 10-fold excess of hydroxyalkyl acrylate relative to an equimolecular mixture of α-oxide and tertiary amine .

 The conclusions made are confirmed experimentally. Simultaneous analysis on two detectors (refractometric and ultraviolet) of oligomers washed from low molecular weight components of the reaction systems and dried in vacuum, allowed us to identify the presence of a C = C bond by peak with a wavelength of 210-213 nm, regardless of the nature of the initiator.

The hetero chain structure of the oligomers obtained by the proposed method is confirmed by NMR spectroscopy. NMR spectra were recorded on a Bruker AC-200 P NMR spectrometer at 25 ^{° C.} with accumulation of signals. For measurements, saturated solutions of oligomers in carbon tetrachloride were used.

Indeed, ¹ H NMR spectra of the soluble and insoluble in ethanol fractions of the GEA oligomer (Example 3) [δ, ppm: 4.12 (br. M, 2H, CH ₂ -O); 3.58 (br m, 2H, CH ₂ -O); 3.47 (br m, 2H, CH ₂ -O-); 2.42 (br. M, 2H, —CH ₂ —CO)] and an FUEA oligomer (Example 4) [δ ppm: 7.06 (br., 5H, C ₆ H ₅ ): 4, 01 (br.m. 4H. O-CH ₂ CH ₂ -O); 3.79 (br. M., 2H, CH ₂ -O), 2.42 (br. M., 2 H -CH ₂ -CO-)] and ¹³ C NMR spectra of the oligomer in DMF FUEA-D solution ₇ [δ, ppm: 32.3 (-CH ₂ CO); 45.7 (CH ₂ -O); 61.7 (CH ₂ -O); 62.8 (CH ₂ -O); 126.1, 126.7, 128.4, 141.0 (C ₆ H ₅ ); 154.2 (C = N); 170.2 (C = O)] show the presence in the oligomer of four nonequivalent CH ₂ groups corresponding to the hetero-chain nature of the oligomers.

 In agreement with this fact, there are data on the determination of the concentration of functional groups: C = C bonds by the method of catalytic hydrogenation in a thin layer [Rylander P.N. Catalytic Hydrogenation over Platinum Metals. New York: Acad. Press, 1967] and OH groups by IR spectroscopic and chemical methods for the reaction of urethane formation [Gafurova MP, Lodygina VP, Grigoryeva VA, Cherny GI, Komratova VV, Baturin S .M. // High Molecule. conn. A. 1982. T. 24. 4. S. 858].

An exception is the FUEA oligomer obtained in Example 6. Compared to the 4th example, additional signals appear in the ¹ H NMR spectrum of this oligomer: 2.16 (br. M, 2H, CH ₂ -CH) and 1.96 ( tsp, 1H, CH ₂ -CH). Evaluation showed that in this sample there are ~ 70% heterochain and ~ 30% carbochain structures. This is due to the following. FUEA is synthesized by non-catalytic interaction of GEA with phenylisocyanate at an equifunctional ratio and at ≤60 ^o C for 8 s. The 4-methoxyphenol present in the GEA as an inhibitor also interacts with the phenyisoyanate to form the corresponding urethane-containing derivative, and its relative concentration is almost halved. In this regard, during the oligomerization of FUEA, despite careful isolation from moisture and oxygen in the air (all operations are carried out in an argon stream), partly the process goes along the carbon chain path. In each link of the macromolecule of the carbochain structure there is an alkyl-aryl substituent containing an active proton. The solubility of such oligomers in ethanol is significantly higher than the oligomers of the hetero chain structure. Therefore, less stringent conditions for washing low molecular weight products, as in example 6 compared with example 4, become insufficient to completely remove the carbochain fraction of the oligomer, which is confirmed experimentally.

Thermomechanical tests of the FUEA macromonomer showed that its glass transition temperature was 10 ^o С (example 5), and the additional heat treatment at 100 ^o С for 7 h did not lead to a significant change in molecular characteristics (example 7), which indicates the absence of thermally initiated crosslinking upon heating up to 100 ^o C. Note that the introduction of an additional amount of inhibitor in the FUEA monomer allows you to completely prevent the carbon chain path of its oligomerization.

 Thus, new heterochain reactive oligomers with wide possibilities for their further transformation and use were obtained.

Claims (4)

1. Reactive hetero chain oligomers based on proton-containing acrylic derivatives of the general formula
CH ₂ = CH — C (O) O- (CH ₂ ) _n —X— [CH ₂ —CH ₂ —C (O) O- (CH ₂ ) _n —X—] _m H,
where X is —O—, —O — C (O) —N (Ph) -;
n is 2-10;
m = 2-15.  2. The method of producing reactive heterochained oligomers according to claim 1 by anionic polymerization of acrylic derivatives in the presence of an initiator, characterized in that proton-containing acrylic derivatives are taken as monomers, anionic polymerization is carried out in an inert medium in the presence of initiators selected from the group of alkali metals or their derivatives , a mixture of α-oxide and a tertiary amine, the molar ratio of components in which is taken in the range of 0.5-1.5, respectively, the ratio of monomer and initiator being selected from the interval la (10-40) ÷ 1, respectively.  3. The method according to claim 2, characterized in that their derivatives are taken as alkali metal derivatives. 4. The method according to claim 2, characterized in that the polymerization is carried out at 40-80 ^o C.

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